Daily Report #4757

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT***** #4757

PERIOD COVERED: 5am December 15 - 5am December 16, 2008 (DOY
*************************** 350/1000z-351/1000z)

OBSERVATIONS SCHEDULED

FGS 11704

The Ages of Globular Clusters and the Population II Distance Scale

Globular clusters are the oldest objects in the universe whose age can
be accurately determined. The dominant error in globular cluster age
determinations is the uncertain Population II distance scale. We
propose to use FGS 1r to obtain parallaxes with an accuracy of 0.2
milliarcsecond for 9 main sequence stars with [Fe/H] -1.5. This will
determine the absolute magnitude of these stars with accuracies of
0.04 to 0.06mag. This data will be used to determine the distance to
24 metal-poor globular clusters using main sequence fitting. These
distances (with errors of 0.05 mag) will be used to determine the ages
of globular clusters using the luminosity of the subgiant branch as an
age indicator. This will yield absolute ages with an accuracy 5%,
about a factor of two improvement over current estimates. Coupled with
existing parallaxes for more metal-rich stars, we will be able to
accurately determine the age for globular clusters over a wide range
of metallicities in order to study the early formation history of the
Milky Way and provide an independent estimate of the age of the
universe.

The Hipparcos database contains only 1 star with [Fe/H] -1.4 and an
absolute magnitude error less than 0.18 mag which is suitable for use
in main sequence fitting. Previous attempts at main sequence fitting
to metal-poor globular clusters have had to rely on theoretical
calibrations of the color of the main sequence. Our HST parallax
program will remove this source of possible systematic error and yield
distances to metal-poor globular clusters which are significantly more
accurate than possible with the current parallax data. The HST
parallax data will have errors which are 10 times smaller than the
current parallax data. Using the HST parallaxes, we will obtain main
sequence fitting distances to 11 globular clusters which contain over
500 RR Lyrae stars. This will allow us to calibrate the absolute
magnitude of RR Lyrae stars, a commonly used Population II distance
indicator.

FGS 11870

Calibrating FGS1R's Optical Field Angle Distortion (OFAD), Second
Epoch

This proposal gathers the data needed to calibrate the optical field
angle distortions in FGS1r to the level of accuracy required for
astrometry science. Selected stars from the galactic cluster M35 are
repeatedly observed in POSITION mode by FGS1r with F583W filter at a
variety of spacecraft pointings and telescope roll angles. Ideally the
observations are to occur at a time when this ecliptic star field is
near the anti-sun direction so that HST's roll angle is unconstrained.
Unfortunately this is not possible under two gyro operations.
Therefore, the observations in this proposal are somewhat very
constrained in roll. However, this test should suffice as an adequate
update to the original FGS1r OFAD that executed in December 2000. For
each visit, the desired telescope pointing is specified by POS TARG
and ORIENT special requirements.

FGS 11943

Binaries at the Extremes of the H-R Diagram

We propose to use HST/Fine Guidance Sensor 1r to survey for binaries
among some of the most massive, least massive, and oldest stars in our
part of the Galaxy. FGS allows us to spatially resolve binary systems
that are too faint for ground-based, speckle or optical long baseline
interferometry, and too close to resolve with AO. We propose a
SNAP-style program of single orbit FGS TRANS mode observations of very
massive stars in the cluster NGC 3603, luminous blue variables, nearby
low mass main sequence stars, cool subdwarf stars, and white dwarfs.
These observations will help us to (1) identify systems suitable for
follow up studies for mass determination, (2) study the role of
binaries in stellar birth and in advanced evolutionary states, (3)
explore the fundamental properties of stars near the main
sequence-brown dwarf boundary, (4) understand the role of binaries for
X-ray bright systems, (5) find binaries among ancient and nearby
subdwarf stars, and (6) help calibrate the white dwarf mass - radius
relation.

WFPC2 11113

Binaries in the Kuiper Belt: Probes of Solar System Formation and
Evolution

The discovery of binaries in the Kuiper Belt and related small body
populations is powering a revolutionary step forward in the study of
this remote region. Three quarters of the known binaries in the Kuiper
Belt have been discovered with HST, most by our snapshot surveys. The
statistics derived from this work are beginning to yield surprising
and unexpected results. We have found a strong concentration of
binaries among low-inclination Classicals, a possible size cutoff to
binaries among the Centaurs, an apparent preference for nearly equal
mass binaries, and a strong increase in the number of binaries at
small separations. We propose to continue this successful program in
Cycle 16; we expect to discover at least 13 new binary systems,
targeted to subgroups where these discoveries can have the greatest
impact.

WFPC2 11289

SL2S: The Strong Lensing Legacy Survey

Recent systematic surveys of strong galaxy-galaxy lenses {CLASS,
SLACS, GOODS, etc.} are producing spectacular results for galaxy
masses roughly below a transition mass M~10^13 Mo. The observed lens
properties and their evolution up to z~0.2, consistent with numerical
simulations, can be described by isothermal elliptical potentials. In
contrast, modeling of giant arcs in X-ray luminous clusters {halo
masses M ~10^13 Mo} favors NFW mass profiles, suggesting that dark
matter halos are not significantly affected by baryon cooling. Until
recently, lensing surveys were neither deep nor extended enough to
probe the intermediate mass density regime, which is fundamental for
understanding the assembly of structures. The CFHT Legacy Survey now
covers 125 square degrees, and thus offers a large reservoir of strong
lenses probing a large range of mass densities up to z~1. We have
extracted a list of 150 strong lenses using the most recent CFHTLS
data release via automated procedures. Following our first SNAPSHOT
proposal in cycle 15, we propose to continue the Hubble follow-up
targeting a larger list of 130 lensing candidates. These are
intermediate mass range candidates {between galaxies and clusters}
that are selected in the redshift range of 0.2-1 with no a priori
X-ray selection. The HST resolution is necessary for confirming the
lensing candidates, accurate modeling of the lenses, and probing the
total mass concentration in galaxy groups up to z~1 with the largest
unbiased sample available to date.

WFPC2 11944

Binaries at the Extremes of the H-R Diagram

We propose to use HST/Fine Guidance Sensor 1r to survey for binaries
among some of the most massive, least massive, and oldest stars in our
part of the Galaxy. FGS allows us to spatially resolve binary systems
that are too faint to observe using ground-based, speckle or optical
long baseline interferometry, and too close to resolve with AO. We
propose a SNAP-style program of single orbit FGS TRANS mode
observations of very massive stars in the cluster NGC 3603, luminous
blue variables, nearby low mass main sequence stars, cool subdwarf
stars, and white dwarfs. These observations will help us to (1)
identify systems suitable for followup studies for mass determination,
(2) study the role of binaries in stellar birth and in advanced
evolutionary states, (3) explore the fundamental properties of stars
near the main sequence-brown dwarf boundary, (4) understand the role
of binaries for X-ray bright systems, (5) find binaries among ancient
and nearby subdwarf stars, and (6) help calibrate the white dwarf mass
- radius relation.

WFPC2/ACS/SBC 11957

Hubble Investigation of Asteroid 21 Lutetia in Support of the Rosetta
Mission Flyby

The Rosetta mission is gearing up for a flyby encounter with the
large, main belt asteroid 21 Lutetia, with closest approach on 2010
June 10. The next opposition, on 2008 December 1, is our last
opportunity to make observations in time to affect the planning of the
Rosetta program. We request a total of 5 orbits of Hubble observing
time (2 using ACS/SBC and 3 using WFPC2) to characterize the UV albedo
of Lutetia, to search for any dust debris near the main body, and to
perform a deep search for companions. Even one orbit of Hubble time
would provide valuable data for planning the Rosetta-Alice ultraviolet
spectrometer observations, and 2 orbits are sufficient to characterize
the far-UV albedo, but a 5-orbit program provides a richer scientific
investigation with potentially much broader implications, both
scientifically and for Rosetta planning.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be
investigated.)

HSTARS: (None)

COMPLETED OPS REQUEST:

18370-0 - Adjust NCS CPL Setpoint to (15 degC)

COMPLETED OPS NOTES: (None)

*********************** SCHEDULED***** SUCCESSFUL

FGS GSacq************** 14***************** 14
FGS REacq************** 00***************** 00
OBAD with Maneuver **** 28***************** 28

SIGNIFICANT EVENTS:

Flash Report: Flash: NCS Restart

The Circulator was successfully started at 350/13:45

The CPL reservoir setpoint was brought down to 15 deg C during the
evening/overnight period at a rate of 2 deg/hour